"Why am I the one who has to die? If I die, the world will still function as usual. It's as if my existence doesn't matter."
"In that case, I'll give you a choice. How about letting the world die with you?"
"... Okay."
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The summary of the story is that a very useless male protagonist said something to destroy the world in order to make up for his slip of the tongue, and followed his companions to protect the world.